novel and convenient strategy for the enantioselectivesynthesis of γ-lactam derivatives via N-heterocyclic carbene catalyzed formal [3 + 2] annulation of enals with 2-aminoacrylates is disclosed. This activation mode provides a complementary approach to the synthesis of various γ-lactam derivatives in good yields with excellent diastereo- and enantioselectivities. In this process, two consecutive stereocenters
Direct Catalytic Chemoselective α-Amination of Acylpyrazoles: A Concise Route to Unnatural α-Amino Acid Derivatives
作者:Keisuke Tokumasu、Ryo Yazaki、Takashi Ohshima
DOI:10.1021/jacs.5b11773
日期:2016.3.2
carboxylic acid oxidation state substrate, while preactivation by a stoichiometric amount of strong base has been used in catalytic α-aminations. The simultaneous activation of both coupling partners, enolization and metal nitrenoid formation, was crucial for obtaining the product, and wide functional group compatibility highlighted the mildness of the present catalysis. The bidentate coordination mode was
Synthesis of Cyclopentenes, Pyrroles, and Thiophenes via a Sequence of Propargyl–Allenyl Isomerizations, Michael Additions, and Intramolecular Wittig Reactions
作者:Guoqing Zhao、Qianyun Zhang、Hongwei Zhou
DOI:10.1021/jo501867h
日期:2014.11.21
simple, readily available propargylphosphonium salts through propargyl–allenyl isomerization. We developed an efficient synthesis for cyclopentenes, pyrroles, and thiophenes via a sequence of propargyl–allenyl isomerizations, Michael additions, and intramolecular Wittig reactions.